/**
 * Copyright 1996-2014 FoxBPM ORG.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * @author ych
 */

package org.foxbpm.engine.query;

import java.util.List;

/**
 * Describes basic methods for querying.
 * 
 * @author Frederik Heremans
 */
public interface Query<T extends Query<?, ?>, U extends Object> {

	/**
	 * Order the results ascending on the given property as defined in this
	 * class (needs to come after a call to one of the orderByXxxx methods).
	 */
	T asc();

	/**
	 * Order the results descending on the given property as defined in this
	 * class (needs to come after a call to one of the orderByXxxx methods).
	 */
	T desc();

	/** Executes the query and returns the number of results */
	long count();

	/**
	 * Executes the query and returns the resulting entity or null if no entity
	 * matches the query criteria.
	 * 
	 * @throws ActivitiException
	 *             when the query results in more than one entities.
	 */
	U singleResult();

	/** Executes the query and get a list of entities as the result. */
	List<U> list();

	/** Executes the query and get a list of entities as the result. */
	List<U> listPage(int firstResult, int maxResults);

	/**
	 * 获取查询数据分页列表
	 * 
	 * @param pageIndex
	 *            页码数
	 * @param pageSize
	 *            显示行数
	 * @return 分页列表
	 */
	List<U> listPagination(int pageIndex, int pageSize);
}
